The skin is an organ composed of several layers of tissues. It comprises three principal parts. The superficial and thinnest part, is called the epidermis. It is attached to an internal layer that is the thickest part, called the dermis. An even deeper layer is called the hypodermis.
Among other things, the skin acts as a protective envelope around the body. It is one of the largest organs in terms of its area and mass: in adults, about 2 m² and 5 kg.